The lawyer defending a veteran Bronx detective caught perjuring himself after a savvy 17-year-old secretly recorded the officer questioning him on an MP3 player said today that finding his client guilty would “have a chilling effect on any detective” and that the cop should instead get a medal.

In the trial against Det. Christopher Perino, 43, began this morning in Bronx Supreme Court, his lawyer Murray Richman argued that the 22-year NYPD veteran has no history of violence and was just doing his job.

“A finding of guilt in this particular instance will have a chilling effect on any detective. It’s just the wrong thing to do,” said Richman.

The Bronx DA, however, said the case is easy because the crime was caught on tape.

Perino, 43, faces 12 counts, including perjury, that could cost the married father of four his pension and his freedom, while Erik Crespo is currently serving seven years after prosecutors let him plead guilty to weapons possession.

At Crespo’s trial two years ago, Perino stated emphatically that he never interviewed the suspect before his aunt and mother had arrived at the 44th Precinct station house. Prosecutors were blindsided when Crespo’s lawyers introduced the MP3 recording as evidence.

Assistant DA Larry Hartstein said Perino will be found guilty of all the counts, especially after he denied quizzing the teen.

“The crime is going to be played before the court,” he said. “I think it’s very clear… that he perjured himself,” he said.

He noted that because of the cop’s alleged lies, Crespo, who also took the stand today wearing his orange prison jumpsuit, got to plead to a lower charge.

But Richman went out of his way to point blame on Crespo, saying the teen tried to flee the country and was eventually picked up at Kennedy Airport .

“He’s trying to get a gun off the streets,” Richman said of Perino’s actions. “If anything, he should get a commendation as one good cop… This is devastating to the police officers of the city of New York.”